Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
van hanh » van thanh, ban hanh, van anh
thuc van » thuc vat, thuc dan, thuc va
tu sach » thu sach, su sach, te sach
tai cua » thai cua, tai cuc, tri cua
tai cuu » tai cuc, tai buu, thai cua
sach ty » sach y, sach tu, sach thu
hieu he » hieu ve, hiem he, hieu le
nang ma » tang ma, sang ma, nang cao
he nam » ha nam, nghe nam

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ty ((nang ma) or (nang x)) hoi. hieu he nam thuc van hanh ((tai cuu) or (tai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((nang ma) OR (nang x)) hoi. hieu he nam thuc van hanh ((tai cuu) OR (tai cua)) tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((nang ma) or (nang x)) hoi. hieu he nam thuc van hanh ((tai cuu) or (tai cua)) tre*.